There are several instances in which you'd want to delete a page:
There is no quick and easy way to delete pages.
If you just made a typo in the pagename or want to move a page's content somewhere else (e.g. to a subpage) then request a renaming on Page Name Change Requests. This preserves the page's history!
If you would like to have the page deleted then list it in the "obsolete pages" section of Wiki orphans #3.
Alternatively, write "request for deletion" into the page. This way others can then revise the page and decide to either leave or keep the request. Admins are going to delete such pages, based on the history of the request.
Search for pages containing that phrase.
You might consider going the route MeatballWiki is taking. See http://usemod.com/cgi-bin/mb.pl?PageDeletion.